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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 12 |
| 6 | 64 |
| 7 | 391 |
| 8 | 2617 |
| 9 | 18738 |
| 10 | 141483 |
| 11 | 1116801 |
| 12 | 9160502 |
| 13 | 77745060 |
| 14 | 680550918 |
| 15 | 6129635386 |
| 16 | 56699324213 |
| 17 | 537823602765 |
| 18 | 5225075478099 |
| 19 | 51939709551433 |
| 20 | 527829047648887 |
| 21 | 5479728265490353 |
| 22 | 58079392804968241 |
| 23 | 628114208288086710 |
| 24 | 6927692801388774583 |
| 25 | 77887967322146451681 |
| 26 | 892270205641708989800 |
| 27 | 10410949755661589229619 |
[1,1,1,1,3,12,64,391,2617,18738,141483,1116801, 9160502,77745060,680550918,6129635386,56699324213, 537823602765,5225075478099,51939709551433, 527829047648887,5479728265490353, 58079392804968241,628114208288086710, 6927692801388774583,77887967322146451681, 892270205641708989800,10410949755661589229619] |